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Old 01-24-2016, 10:50 PM   #1
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Question DEF

just wondering if anything happens when you run out of def fluid, not much in the manuals on this Tuscany xte 36mq

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Old 01-24-2016, 10:53 PM   #2
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Try this:
What will happen if my truck runs out of Diesel Exhaust Fluid (DEF)?

The U.S. Environmental Protection Agency requires vehicle manufacturers to put measures in place to ensure that vehicles cannot run without Diesel Exhaust Fluid (DEF). Before a truck's DEF tank runs empty the driver is given a series of alerts on their dashboard displays (much the same way as if they were running low on diesel). Generally speaking, when the DEF tank level drops below 10% an amber warning lamp will come on, at 5% this lamp starts flashing and below 2.5% a solid amber warning light is displayed.
If the truck is allowed to run out of DEF the engine's power is reduced, a solid red warning will be displayed and the vehicle speed will be limited to 5 mph until the DEF tank is refilled.

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Old 01-24-2016, 11:31 PM   #3
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Yep ^^^

It will go into a few stages of reduced power/speed until finally just idle speed.

You gotta look in the Freightliner manual for that info. Keep an eye on the level meter in the dash and don't allow it to go empty. Keep a few gallons handy in the basement storage compartment for emergencies. If you weren't already aware, truck stops have def dispensers along side the fuel pumps, top off your def tank when fueling up. Truck stop def is really cheap, like $2.75 a gallon. No excuses to run out.
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Old 01-25-2016, 04:54 AM   #4
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We always keep two jugs on broad just in case, have heard and read that running out will damage exhaust system and is costly to fit.
Mark & Shaleen
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Old 01-25-2016, 06:37 AM   #5
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The thought of limping along the shoulder at 5 mph scares the cra* out of me !
You just don't use it up that fast, that you should ever get to that point. As others have said, carry a spare jug with you. You can purchase at any Walmart, Truck Stop, or Auto Parts store.
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Old 01-25-2016, 07:00 AM   #6
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Just be sure to run it down enough to keep it fresh, don't put the coach into storage with a full tank, I read a lot on this & IMO you should try & keep the DEF as fresh as possible.
I bought a couple of jugs & funnel from the DEF guy you see on this website & fill them at the Pilot when taking the coach out of storage, they work out very well.
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Old 01-25-2016, 08:45 AM   #7
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Old 01-25-2016, 10:05 AM   #8
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I don't think "freshness" is much of a concern for most RVers. The "shelf life" of DEF is at least one year at temperatures anywhere in the range of 10-90 degrees. Longer at low temperatures, since heat seems to be the primary cause of degradation. Cummins says two years if the temperature never exceeds 75 degrees.
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Old 01-26-2016, 06:54 AM   #9
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I'm one of those RV'rs who go to Florida & put there coach in storage for 6 months, the temperature is 80-90 almost every day.
Shelf life should be one year ?
Again IMO I don't take a chance on it not crystallizing.
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Old 01-26-2016, 08:05 AM   #10
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At the FMCA rally in Madison this past summer one of the chassis manufacturers said they liked to size the DEF tank to last at least 4 tanks of fuel. We're talking thousands of miles, at least one coast to coast cross country trip. (I've calculated we could travel about 4500 miles on our 10 gallon DEF tank) Barring a catastrophic failure, if you run our of DEF, well, whatever the consiquences, you brought it on yourself.

I'd like to offer a counter point to those that suggest storing the coach with a minimal amount of DEF in the tank (for fear of spoilage). I'd top the tank off, right to the filler cap. No air in the tank, no opportunity to crystalize. I can envision a ring of white crystals growing around the inside of the tank at the fluid level otherwise. Any real experts care to weigh in?
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Old 05-07-2016, 01:35 PM   #11
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You will get a notice on your information panel that won't go off until you put some DEF in.
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Old 05-07-2016, 01:44 PM   #12
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We set in Tampa for six months with full def tank never had a problem.
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Old 05-07-2016, 01:50 PM   #13
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Yes, something happens and you won't like it.
I might suggest that you sign up for the Freightliner class in Gaffney. This year might be full but you can put your name on a cancellation list. Better yet try and find a class that is near your annual maintenance so you can have that done while n class.
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Old 05-07-2016, 03:36 PM   #14
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My Freightliner/Cummins service center flat out told me to never park MH for any length of time without the DEF tank completely full.

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